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  <title>Document</title>
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<body>
  <script>
    // let num = 10
    // num = num + 1
    // num += 1
    // // 1. 前置自增
    // let i = 1
    // ++i
    // console.log(i)

    // let i = 1
    // console.log(++i + 1)
    // 2. 后置自增
    // let i = 1
    // i++
    // console.log(i)
    // let i = 1
    // console.log(i++ + 1)

    // 了解 
    let i = 1
    console.log(i++ + ++i + i)
  </script>
</body>

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